I bought this coffee grinder to use in combination with my piston machine with single-wall filter holders (non-pressurized). This device is absolutely not suitable for that, because it can't grind coffee beans far enough. The description indicates that this coffee grinder can grind the beans very finely, but "very fine" is apparently a flexible term. If you are looking for a coffee grinder for filter coffee and/or a cafetiere, then this device is an excellent choice. For making espresso I would look at other options: in the finest setting it just manages to make an acceptable espresso with a double-walled filter holder (pressurized), but if you have beans that need to be ground a little finer, then you can you quickly reach the limit of this device.
Unfortunately, I had to send the device back (which was handled very neatly by Coolblue), but that doesn't make this coffee grinder a bad choice. This one was just not suitable for my purpose and I probably should have looked into what is meant by "very fine".